Grain-Chaff separation in a vertical air stream

Abstract

Theoretical and experimental studies were made of the separation of harvested materials in a vertical air stream. Grain and either polystyrene balls (simulating chaff) or actual sieve materials were injected at rates comparable to those occurring in combine harvesters. The results suggest that, not only are air velocity and feed rate important in determining the effectiveness of separation and the level of grain loss, so also are the speed and direction (relative to the main air stream) of the injected material.